The present invention relates to thrust bearings. More particularly, the present invention relates to piloting arrangements for thrust bearing washers. The invention lends itself to use in current swashplate air conditioning compressors, but may be applied in compressors of various types and configurations.
The current practice in swashplate air conditioning compressors uses thrust washers on each side of thrust bearings that are piloted on a compressor main shaft. An example of a fixed displacement compressor of this type is illustrated in section in FIGS. 1 and 2.
Referring to FIG. 1, the compressor generally comprises a main shaft 10, piston connecting portion 14, piston end portions 16, half ball shoes 18, radially loaded roller bearings 20 and 22, thrust washers 24 and 26, roller thrust bearings 28, and swashplate 30 positioned within a housing 50. FIG. 2 is a plan view of an illustrative compressor housing 50 with which the present invention is utilized. The housing 50 includes a face 52 with a shaft bore 54, a plurality of fluid passages 56 and a plurality of piston cylinder bores 58.
As can be seen in FIG. 1, the thrust washers 24 and 26 are piloted off of the main shaft 10. The piloting of the thrust washers 24 and 26 on the compressor main shaft 10 results in relative rotation between the shaft outer diameter and the bore of one of the washers. Special finishing processes for the washer bore (such as fine blanking, for example) are often used in order to prevent excessive wear between the washer bore and the shaft.
The current practice with thrust washers piloted on the main shaft also hinders lubricant from flowing freely to the thrust bearing bore and radially loaded roller bearing. Roller thrust bearings, by their nature, tend to pump lubricant from the bore toward the outer diameter. A clear path under the thrust washer is desired to allow free pumping action of lubricant through the adjacent radially loaded roller bearing and out through the thrust bearing.